Periodic polar vortices in BaTiO3/SrTiO3 superlattices monolithically grown on silicon

Abstract

Abstract Polar textures in ferroelectric superlattices have been so far reported almost exclusively in PbTiO 3 -based systems and predominantly on oxide substrates. Owing to their nanometer-scale dimensions and emergent functionalities, whirling topological polar textures would be especially compelling when realized on silicon with Complementary-Metal-Oxide-Semiconductor-compatible materials. Here, we demonstrate the stabilization of vortex tubes in BaTiO 3 /SrTiO 3 superlattices epitaxially grown on silicon. The vortices in each BaTiO 3 layer order along the < $$110$$ 110 > BaTiO3 crystallographic directions, forming an in-plane 90-degree stripe pattern. This polar configuration represents the ground state of the system as shown by phase field modelling and further validated by temperature dependent X-ray diffraction. Phase field modelling shows a strong dependence of the domain morphology on the strain and highlights the elastic and electrostatic coupling of the BaTiO 3 and SrTiO 3 layers. Our findings expand the materials and substrate platforms known to host polar topological textures, opening new opportunities for integrating complex ferroelectric states with silicon-based technologies.